Conventions used

There are a number of text conventions used throughout this book.

Code in text: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Each PC has a unique IP address within the same subnet (192.168.1.x), which allows them to communicate with each other through the switch"

A block of code is set as follows:

# These lines stack two password type modules. In this
# example,theuser is given 3 opportunities to enter a
# strong password. The"use_authtok" argument ensures
# that the pam_unix module does not prompt for
# a password, but instead uses the one provided
# by pam_cracklib.
passwd password required pam_cracklib.so retry=3 minlen=12 difok=3
vpasswd password required pam_unix.so use_authtok

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

# The following line keeps a history of the last 5 passwords.
password required pam_pwhistory.so remember=5

Any command-line input or output is written as follows:

show ip interface brief

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "This foundation allows you to set specific, measurable, achievable, relevant, and time-bound (SMART) objectives."

Tips or important notes

Appear like this.